[alsa-devel] Why my linux OS has only 8 sound cards ? How can I modify it ?

[Linus Torvalds]

Chris - you need to pick a better set of people to ask. A mailing
list, right maintainer etc.

Takashi, any idea? Do we have some 8-sound-card limit somewhere?

I do see that we have that odd

        if (card && card->number >= 8)
                return 0; /* ignore silently */

in sound/core/sound_oss.c: snd_register_oss_device(), but it has no
comments. The thing goes back to 2005 with the commit log entry of
"[ALSA] dynamic minors (6/6): increase maximum number of sound cards",
but the value '8'isn't explained.

                Linus


On Tue, Nov 8, 2011 at 12:30 AM, Chris Shen <chris2shen at gmail.com> wrote:
> Hi,everyone!
>   My  version of kernel is linux-2.6.35 .And my board has 10 sounds
> cards.After system was up,I used the comand "aplay -l ".Then console
> would display this:
> **** List of PLAYBACK Hardware Devices ****
> card 0: imx3stack [imx-3stack], device 0: WM8731 WM8731-0 []
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
> card 1: default [C-Media USB Headphone Set  ], device 0: USB Audio
> [USB Audio]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
> card 2: default_1 [C-Media USB Headphone Set  ], device 0: USB Audio
> [USB Audio]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
> card 3: default_2 [C-Media USB Headphone Set  ], device 0: USB Audio
> [USB Audio]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
> card 4: default_3 [C-Media USB Headphone Set  ], device 0: USB Audio
> [USB Audio]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
> card 5: default_4 [C-Media USB Headphone Set  ], device 0: USB Audio
> [USB Audio]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
> card 6: default_5 [C-Media USB Headphone Set  ], device 0: USB Audio
> [USB Audio]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
> card 7: default_6 [C-Media USB Headphone Set  ], device 0: USB Audio
> [USB Audio]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
> card 8: default_7 [C-Media USB Headphone Set  ], device 0: USB Audio
> [USB Audio]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
> card 9: default_8 [C-Media USB Headphone Set  ], device 0: USB Audio
> [USB Audio]
>  Subdevices: 1/1
>  Subdevice #0: subdevice #0
> But,when I used the command "ls /dev/dsp*" ,the console display:
> /dev/dsp   /dev/dsp2  /dev/dsp4  /dev/dsp6
> /dev/dsp1  /dev/dsp3  /dev/dsp5  /dev/dsp7
> when the board is up ,I found have this err "unable to register OSS
> mixer device 8:0" and "unable to register OSS mixer device 9:0" .
> I think the kernel's max sound cards is 8 .How can I modify it ?
> Thank you!
>